html diff in revision view

app/Http/Controllers/PageController.php

@@ -12,6 +12,7 @@
 use BookStack\Repos\PageRepo;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 use Views;
+use Icap\HtmlDiff\HtmlDiff;
 
 class PageController extends Controller
 {
@@ -332,9 +333,19 @@ public function showRevision($bookSlug, $pageSlug, $revisionId)
         $book = $this->bookRepo->getBySlug($bookSlug);
         $page = $this->pageRepo->getBySlug($pageSlug, $book->id);
         $revision = $this->pageRepo->getRevisionById($revisionId);
+
+        $next     = $revision->getNext() ?: $page;
+        $htmlDiff = new HtmlDiff($revision->html, $next->html, true);
+        $diff     = $htmlDiff->outputDiff()->toString();
+
         $page->fill($revision->toArray());
         $this->setPageTitle('Page Revision For ' . $page->getShortName());
-        return view('pages/revision', ['page' => $page, 'book' => $book]);
+
+        return view('pages/revision', [
+            'page' => $page,
+            'book' => $book,
+            'diff' => $diff,
+        ]);
     }
 
     /**

app/PageRevision.php

@@ -32,4 +32,25 @@ public function getUrl()
         return $this->page->getUrl() . '/revisions/' . $this->id;
     }
 
+    /**
+     * Get previous revision
+     * @return \BookStack\PageRevision
+     */
+    public function getPrevious()
+    {
+        if ($id = PageRevision::where('id', '<', $this->id)->max('id')) {
+            return PageRevision::find($id);
+        }
+    }
+
+    /**
+     * Get next revision
+     * @return \BookStack\PageRevision
+     */
+    public function getNext()
+    {
+        if ($id = PageRevision::where('id', '>', $this->id)->min('id')) {
+            return PageRevision::find($id);
+        }
+    }
 }

composer.json

@@ -13,7 +13,8 @@
         "barryvdh/laravel-debugbar": "^2.0",
         "league/flysystem-aws-s3-v3": "^1.0",
         "barryvdh/laravel-dompdf": "0.6.*",
-        "predis/predis": "^1.0"
+        "predis/predis": "^1.0",
+        "icap/html-diff": "^1.1"
     },
     "require-dev": {
         "fzaninotto/faker": "~1.4",